The present invention relates to an insertion socket for use with a flat cable, and more particularly to an insertion-type socket in which an increased contact pressure is applied by terminals provided inside the socket on the flat cable inserted into the socket when the cover of the insertion socket is closed onto the socket. With the insertion socket of the present invention, a large reactive force is generated by the terminals which acts on the cover so that the cover will not accidentally.
Soft flat cables are mainly used in integrated circuit boards to connect different circuits. On a circuit board 14, there is provided with a plurality of relatively small insertion sockets 12 for flat cables 10 to insert thereinto. As can be seen in FIG. 1, each of these insertion sockets 12 includes a cover 13. When the cover 13 is lifted to an open position, as shown by the phantom lines in FIG. 1, the insertion socket 12 has a widened front opening via which a flat cable 10 is inserted into the socket 12. When the cover 13 is in a close position on the insertion socket 12, the flat cable 10 is pressed to contact with terminals 11 received in the insertion socket 12 and thereby provides an electrical circuit. In brief, in the conventional insertion socket 12, the flat cable 10 is brought to contact with and press against the terminals 11 in the insertion socket 12 due to a pressure applied by the cover 13 on the flat cable 10 when the cover 13 is in the close position.
In the conventional insertion socket 12, a contact pressure applied on the flat cable 10 by the terminals 11 is calculated from the following formula (1):
CP=TP/TAxe2x80x83xe2x80x83. . . (1)
wherein CP is the contact pressure applied on the flat cable 10 by the terminals 11, TP is a total pressure against the flat cable 10 when the cover 13 is closed onto the insertion socket 12, and TA is a total area of the flat cable 10 contacting with and being pressed by the cover 13.
The total pressure is generated when the cover 13 is closed onto the insertion socket 12 and it is equal to a total resistance or reactive force from the flat cable 10 to or acted on the cover 13. In the event there is a total pressure or a total reactive force larger than a force retaining the cover 13 to the insertion socket 12, it will result in a loosened cover 13 from the insertion socket 12. That is, there is an upper limit in the value of the total pressure TP in the conventional insertion socket 12 shown in FIG. 1. This limitation prevents the flat cable 10 from being firmly connected to the insertion socket 12.
A primary object of the present invention is to provide an insertion socket that has a structure enabling an increase contact pressure applied by terminals received in the socket on a flat cable inserted into the socket, so that the flat cable would not easily separate from the insertion socket.
To achieve the above and other objects, the insertion socket for flat cable of the present invention mainly includes a socket main body defining a plurality of terminal cavities therein, a cover connected to a top of the socket main body to pivotally turn between an open and a close position, and a plurality of terminals separately received in the terminal cavities. Each of the terminals has a rear end projected from a rear side of the socket main body to provide a connecting pin, and a front barb portion that is formed at a lower side with a plurality of backward extended barbs. When the cover is pivotally turned downward to the close position on the socket main body, it contacts with and applies a pressure on the barb portions of the terminals to cause the barbs on the barb portions to contact with and press against a flat cable inserted into the socket main body and located below the barb portions. And, an area on each of the barb portions contacting with the cover in the close position is a specially determined bevel surface, such that a reactive force acted by the barb portions of the terminals on the cover in the close position on the socket main body does not result in a lifted cover.